Weird idle issue once again. Car fully warm and all accessories off. Just driving about in the city and sometimes idle is at 1100 and sometimes it's at 750-850. There is no pattern I can find, just idles where it feels like when I stop. Also if I look closely it's not idling at one number. I can see the needle moving slightly up and down when I look closely. I also did have one incident where it was at 750 and was dipping down to 400 trying to die out.

Dashpot was just replaced. Motor just ended break in period. I couldn't tell you vacuum readings because my gauge still refuses to function correctly. When motor was fresh we checked One of the sensors and it was within spec. I think it was either ISC or TPS. Temps are at 180 the whole time so it's not the fans cycling.

 

Does electrical load have any impact on it?
IE turn the headlights on, plus heater blower fan- does this alter the idle or stabilize it?

Had this issue with one of my JDM RHD cars, but never got to the bottom of it before I got rid of the car.

 

No effect when it's at the 1k idle. When it's at 750-850 idle does jump around 900-1000 when electrical load is added. Same thing happens when fans turn on at 203 F

 

Could be lots of things. A bad clutch switch will cause idle issues. Thats what I would check first.

 

Heres what my clutch switch looks like, Im not sure what to look for. This is with the pedal depressed. But I dont have any difference if my foot is on the clutch or not with my issues.

 

If the pin goes in and out normally, its probably ok. It is spring loaded. Just push it in and make sure it springs back out.

If you think it may be bad, remove it and take it apart to clean it. Gently pry the metal tabs back to take it apart. Clean it up, and replace the spring with one from a ball point pen if the spring looks bad.

 

do your lights dim when the rpms drop down? interior or exterior?

 

I can check. The only time I noticed that was when I used my car to jump my dads truck. Battery is brand new too.

 

Also I know of a buddy that had his oil pressure drop to when the rpms fell down to 500 when he got off the gas, does your needle drop orrpms fall then catch or does it just fluctuate

 

Ensure the TPS is properly adjusted. A sticking thermowax can cause issues as well. Especially if the TPS was adjusted while it was sticking

https://www.rx7club.com/3rd-generati...g-more-170731/

Also ensure the idle bleed screw under the throttle body isn't turned more than 1 full turn from completely shut. It's tucked under the input side of the throttle body, and runs parallel with how air flows.

As mentioned, the clutch switch, and the neutral switch both can cause the ECU not to initiate its idle circuit. If you have a Power FC, you can confirm your clutch switch & neutral switch are working properly with the Power Commander. It displays the sensor's on/off state. Also remember, there are two clutch switches. The lower plunger type one is simply a starter relay switch for safety. The switch that affects the ECU is attached to the pedal closer to the firewall.

 

Needle doesnt drop when off throttle. My new dashpot is working correctly and drops it slowly. Although I should adjust it because it idles high at first then slowly goes to either the 1100 rpm idle or the 750 idle.

The picture that I took, is that is the correct switch? Also I did notice that sometimes I can hear some backfire out of the tailpipe downshifting. Just figured im running rich but I guess it can be related. Ill check the bleed screw and TPS when I find time. Ill be buying a Power FC to help with situations like this. I was hesistant on buying it since it doesnt retard timing on knock situations, I just like how the stock ECU can do that for safety.

 

Yes, that is the correct clutch switch. The other one interacts with your starter.

 

Looks like I still get idle surging when car is cold coming to a stop. Guess dashot needs tweaking since I just put it in there. I didn't do the part where someone's holds the rev at 2.5k.

 

Car died randomly after I started it after work today.

 

What were noticeable things that happened to the car before it died.

Mine use to have the issue when I would blip the throttle the rpms would drop, cat shook, and it died.

Fixed it by adjusting the dashpot

 

It was weird, just started her up it idled normally just like any cold start and just went dead. No bucking or anything. No CEL and the only code I have thats being thrown is AWS because I don't have that system in there. Going to mess with all the adjustments today and see if I can fix it.

 

Also would a broken throttle cable bracket cause some problems? Mine broke when I dropped the motor in. One of my brackets does exist still.

 

I closed my air bleed screw to half a turn. I am now idling at 400-500 fluctuating. Also backfires on decel. Didnt get a chance to mess with TPS because had a different issue rise.

Also I'll be getting a power fc next week.

 

I would adjust your idle , that is WAY to low

Min I would do 850, 900 is better

Theres a screw on the left side of the throttle body, it's very small and requires a flat head. You have to unscrew the nut on it first, adjust, then re tighten

 

Yeah ended up dying right when I got to work. I'll just open the air bleed more.

 

if youre keeping your idle that low, youll keep having problems

 

It was unintentional. Lol

 

had the EXACT same problems. Just like you ended up getting a PFC (I was hoping it might help diagnose the problem). Installed it last week, changed nothing, and now my idle is rock solid (and cold start issues have gone away). Wish I could explain it, maybe there was some problem with my stock ECU??? Hopefully you'll have the same experience and the PFC will 'just fix it'.

Justin

 

Yeah to my understand a power fc doesn't need all of the stock crap to idle the car correctly. Maybe that's why people get rid of a lot of it when they buy a power fc. And I assume that's why when you buy the unit it learns the idle on first start.

 

TPS was out of spec. We realigned it and idle improved a lot. Still have a small issue which is quite weird. Pressing on the brake makes idle drop to a undesirable level. It will also dip down like that sometimes as we'll without the brake. If I blip the throttle it goes back at the intended set idle.

This is a fresh motor. Didnt do any of this during break in, I'm just out of my break in period.